Small computer system interface (SCSI) is a ubiquitous parallel interface standard used for data transfer, typically data transfer between a storage drive and a computer. Contained in the SCSI standard are provisions for logical unit numbers (“LUN”) which are unique identifiers used on a SCSI bus to distinguish between different devices that share that same SCSI bus. Typically, eight devices will be given a unique address ranging from 0-7 for an 8-bit bus or 16 devices will be given a unique address ranging from 0-15 for a 16-bit bus. Commands that are sent to a SCSI controller are routed to their correct destination device based on the LUN assignment information associated with the command.
In some implementations, a SCSI controller may perhaps be embedded in an external drive and additional devices are in turn connected to that drive. In such an environment, the external drive would act as a “bridging” device in that the drive can bridge commands received from a host to devices attached, to the drive, via their assigned LUN. Such a configuration is sometimes employed in automated media changer systems wherein the media changer system is connected to the external drive.
While the SCSI standard is a proven technology and has been utilized for a long period of time, new standards are emerging as alternatives to the SCSI standard. One such emerging standard is the serial ATA (“SATA”) protocol and it may be desirous to implement an SATA drive in place of the SCSI drive in the above-illustrated implementation. However, the SATA protocol does not provide for multiple LUNs. In other words, for some operating systems, it is not possible for multiple LUNs to exist beneath a single target identifier from the perspective of the host operating system. In light of the foregoing, a need in the art exists for methods, apparatuses and systems that allow for, or facilitate, implementation of multiple logical unit numbers in an SATA environment.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.